PPTP WinXp Pro FW

I have a client that wants to connect to the SBS2003 server he has at the home office. I am able to manage this server remotely through a PPTP VPN tunnel from my workstation running Win2K and remotedesktop by point to the name. I also am able to access the server and any of the host on this network with the clients two remote workstations, however, if the Windows Firewall is turned on for these workstations I can only connect to the host by ip. If I turn off the Windows Firewall the host names are resolved correctly. What needs to be set in the Windows firewall to enable name resolution with the firewall turned on? NOTE: I am using the windows VPN PPTP client.